Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are extremely persistent chemicals that are widely distributed in the environment as a result of high chemical stability under normal environmental conditions and extensive use over the last 50 years in commercial and industrial applications including fluoropolymer manufacturing, food packaging, lubricants, water-resistant coating, and fire-fighting foams. PFOS was phased out of production and use in 2002, and US manufacturers eliminated PFOA emissions and product content at the end of 2015. Although emissions have been dramatically reduced in the United Status and Western Europe, it is not clear if global production has changed as there has been a shift in productions to Asia. Some published studies of PFOA and PFOS raised concerns about potential immune system health effects and the NTP received nominations to conduct a review of immune effects for these chemicals.

The NTP conducted a systematic review to evaluate the evidence on exposure to PFOA or PFOS and immune-related health effects to determine whether exposure to either chemical is associated with immunotoxicity for humans. The NTP concludes that both PFOA and PFOS are presumed to be an immune hazard to humans based on a high level of evidence from animal studies that PFOA and PFOS suppressed the antibody response and a moderate level of evidence from studies in humans. The evidence that these chemicals affect multiple aspects of the immune system supports the overall conclusion that both PFOA and PFOS alter immune functions in humans.